Once on a Cisco Catalyst 6509-E, I noticed that the SYSTEM LED on the WS-SUP720-3BXL is lit red.
After connecting to the device, I did not find anything in the logs:
But after the command:
Found the cause – the cable is not connected to the second power supply, that is, it is turned off:
power-supply 2 power-output-fail: failed
SYSTEM can also glow red when the temperature of the sensors is above normal and should be written in the logs. Or, as in my case, the test error of other modules, which can be seen after the “show environment” command.
I will give an example of several commands for diagnostics:
show version show log show logging onboard module 1 show counters ... show counters interface gigabitEthernet 1/1 show module show environment show port show mac show running-config show startup-config show ?
See also my article:
Online diagnostics Cisco Catalyst 6500